health

1. Definition .
   
2. Description .
   
3. Demographics .
   
4. Causes and Symptoms .
   
5. Diagnosis .
   
6. Treatment .
   
7. Prognosis .
8. Prevention .
   
9. The Future .

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Conjunctivitis is an infection or inflammation of the conjunctivae, the
thin clear membranes that cover the white part of the eyeballs and line
the inside of the eyelids.

Conjunctivitis is a medical condition in which the conjunctivae appear
pink or red, and the eyes water and feel irritated. In some cases the eyes may
feel scratchy or itchy as well. Conjunctivitis can be caused by a bacterial,
chlamydial, or viral infection; by seasonal allergies; by a foreign object in the
eye; by a chemical irritant; or by such other medical conditions as dry eye.
There may be mild sensitivity to light, a condition known as photophobia.

There are no exact statistics on the number of cases of conjunctivitis in
the United States each year because the condition has so many possible
causes, but it is the single most common reason for a person’s consulting
an eye doctor. Between 1 and 2 percent of babies born in the United
States each year have ophthalmia neonatorum, a bacterial conjunctivitis
caused by a sexually transmitted disease in the mother.

Conjunctivitis may have a number of different causes. Some are not contagious,
while others can be transmitted from person to person. The
symptoms also vary somewhat depending on the cause:

• Allergic conjunctivitis. Allergic conjunctivitis is caused by pollen,
  dust, and the other types of allergens that cause hay fever and other
  seasonal allergies in some people. Both eyes are usually affected.
  The eyes are usually very watery and itchy in this type of conjunctivitis,
  and the eyelids may swell up or look puffy.
• Viral conjunctivitis. This type of conjunctivitis is contagious and
  often gets started when viruses from an upper respiratory infection
  like a cold are carried into the eye by hand-to-eye contact. The
  infection usually starts in one eye but often spreads to the other
  within a day or two. The discharge from the eye is usually watery.
  A person with viral conjunctivitis is contagious for one to two
  weeks after their symptoms first appear.
• Bacterial conjunctivitis. Like viral conjunctivitis, this type is also
  contagious and can be spread by sexual contact with someone
  infected with gonorrhea or chlamydia as well as by hand-to-eye
  transmission. Pregnant women infected with gonorrhea or chlamydia
  can give their babies a particularly dangerous type of bacterial
  conjunctivitis during childbirth known as ophthalmia
  neonatorum, which can cause blindness if untreated. Bacterial
  conjunctivitis is often accompanied by a gritty or sandy feeling
  in the eyes and a yellowish or grayish pus-filled discharge that
  causes the eyelids to stick together during sleep. Bacterial conjunctivitis
  usually appears within three days after the person is infected
  with the bacteria. Like viral conjunctivitis, it often begins in one
  eye but can spread to the other.
• Chemical splash (toxic conjunctivitis). This type of conjunctivitis
  is noninfectious. It is caused by getting an irritating chemical
  in the eye (such as shampoo or chlorine from swimming in pool water)
  and usually affects only the lower part of the conjunctiva inside
  the lower eyelid. Redness of the affected eye is sometimes
  caused by flushing the eye to wash out the chemical.
• Foreign body in the eye. Like toxic conjunctivitis, this type of
  conjunctivitis is notinfectious. It usually affects only one eye
  and may be accompanied by a mucus-like discharge.
  
• Chronic or recurrent conjunctivitis. Some people develop
  recurrent episodes of conjunctivitis from wearing contact lenses or
  overusing certain types of eye drops. This type of conjunctivitis
  is not contagious.
  
• Conjunctivitis associated with dry eyes or other eye disorders.
  Some eye disorders are associated with a gradual loss of normal tear
  secretions in the eye, which can lead to conjunctivitis.
  
  

In many cases conjunctivitis will clear up by itself in three to four days
without the need to see a doctor. If the condition does not clear by itself,
or if the discharge from the eye contains pus rather than being clear and
watery, the person should see their doctor.
The doctor may take a sexual history or ask about recent exposure
to colds and other viral illnesses or the patient’s use of eye cosmetics or
contact lenses to narrow the diagnostic possibilities. The doctor may
also take a sample of the discharge from the affected eye or eyes for
laboratory analysis in order to determine whether a bacterium or a virus
is the cause.
Severe pain, intense photophobia, and blurred vision are not usually
present in uncomplicated conjunctivitis. A patient with these symptoms
should be examined further for more serious eye disorders, including
glaucoma or inflammation of the interior of the eye. If the patient’s eye
has been irritated by a chemical, the doctor may examine the eye with
a slit lamp to see whether the interior of the eye has also been affected.

Treatment of conjunctivitis depends on the cause of the infection or irritation.
Allergic or seasonal conjunctivitis is usually relieved by applying
cool compresses to the eyes or by using artificial tears. This type of conjunctivitis
can also be treated with antihistamines, steroids, or other antiinflammatory
medications.
Bacterial infections are treated with antibiotic eye ointments or
drops. There are no specific treatments for viral conjunctivitis; the illness
must simply be allowed to go away on its own. Warm compresses or artificial
tears may help to ease the patient’s discomfort. Viral conjunctivitis
may get worse for the first three to five days of the infection and then gradually
get better; it can take as long as three to four weeks for viral conjunctivitis
to clear up completely.
Foreign bodies or chemicals in the eye are usually washed out with
saline solution. A chemical splash involving a caustic substance like lye
is a medical emergency and should be treated by an emergency room
physician or eye specialist as soon as possible.

The prognosis of conjunctivitis depends on its cause. Most people
recover with no problems provided they follow the doctor’s instructions
for their particular type of conjunctivitis and practice good eye hygiene in
general. The only type of conjunctivitis in adults that may cause permanent
loss of vision is a chemical splash injury involving caustic chemicals
such as lye or potash.
Ophthalmia neonatorum, however, can lead to blindness if it is not
treated promptly. The usual treatments for bacterial infections of the eyes
in newborns are silver nitrate eye drops or antibiotic medications.

While it is not always possible to prevent being exposed to people with
upper respiratory infections in one’s school or workplace, one can lower
one’s risk of conjunctivitis by keeping the hands clean, being careful
when touching the eyes, following instructions for the proper use and
cleansing of contact lenses, and avoiding sharing washcloths and other
personal items with others. Additional guidelines for preventing conjunctivitis
are listed in the sidebar.

Conjunctivitis has so many different causes that it is likely to continue to
be a commonplace health concern for the foreseeable future.